From patchwork Mon Oct 14 10:58:25 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ryan Roberts X-Patchwork-Id: 13834846 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 56E4FD1624B for ; Mon, 14 Oct 2024 11:49:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=WYYsCtIDe3FfCiqGTFtQtqmkCpDu+2cX7LKMS9zkbAc=; b=3HI8m/tAeLIVpZvtfyBVM43Rak slq2iudAmMDL8fyyK9kVm2l58mr/HAxzOKjA54XtPLJSfwuFBfQFFjL2hoFuaRQ8Hv28pzUeJcr9v CFgZt0+C/3+shhll98XpRA8BSNeaJntQopx/0zprIw1EMi53ruk52vnssCYYyhqPp5Vywi5TJqSUc R3PVDu+9RSnMcG0SGsnrHNqz6HrRoYl648Iy5RM96ch2Phr6NMCIKM3rBDYo7o7PgMm8twfzw+E2x TXmFApTkZ346fHNtnqYSGl/9mPerundiVcwlctNSca8lPuFeJZrFjvw2L7xVsz8n7O4SewD8qR4Lz SsaVBMTw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1t0JZM-00000004z0E-1P5q; Mon, 14 Oct 2024 11:49:00 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1t0IoJ-00000004no7-0igD for linux-arm-kernel@lists.infradead.org; Mon, 14 Oct 2024 11:00:25 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 65FA91688; Mon, 14 Oct 2024 04:00:52 -0700 (PDT) Received: from e125769.cambridge.arm.com (e125769.cambridge.arm.com [10.1.196.27]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 09E9C3F51B; Mon, 14 Oct 2024 04:00:19 -0700 (PDT) From: Ryan Roberts To: Andrew Morton , Anshuman Khandual , Ard Biesheuvel , Catalin Marinas , David Hildenbrand , Greg Marsden , Ivan Ivanov , Kalesh Singh , Marc Zyngier , Mark Rutland , Masami Hiramatsu , Matthias Brugger , Miroslav Benes , Steven Rostedt , Will Deacon Cc: Ryan Roberts , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org Subject: [RFC PATCH v1 18/57] trace: Remove PAGE_SIZE compile-time constant assumption Date: Mon, 14 Oct 2024 11:58:25 +0100 Message-ID: <20241014105912.3207374-18-ryan.roberts@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20241014105912.3207374-1-ryan.roberts@arm.com> References: <20241014105514.3206191-1-ryan.roberts@arm.com> <20241014105912.3207374-1-ryan.roberts@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241014_040023_357344_C876D1BC X-CRM114-Status: GOOD ( 14.31 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org To prepare for supporting boot-time page size selection, refactor code to remove assumptions about PAGE_SIZE being compile-time constant. Code intended to be equivalent when compile-time page size is active. Convert BUILD_BUG_ON() BUG_ON() since the argument depends on PAGE_SIZE and its not trivial to test against a page size limit. Redefine FTRACE_KSTACK_ENTRIES so that "struct ftrace_stacks" is always sized at 32K for 64-bit and 16K for 32-bit. It was previously defined in terms of PAGE_SIZE (and worked out at the quoted sizes for a 4K page size). But for 64K pages, the size expanded to 512K. Given the ftrace stacks should be invariant to page size, this seemed like a waste. As a side effect, it removes the PAGE_SIZE compile-time constant assumption from this code. Signed-off-by: Ryan Roberts --- ***NOTE*** Any confused maintainers may want to read the cover note here for context: https://lore.kernel.org/all/20241014105514.3206191-1-ryan.roberts@arm.com/ kernel/trace/fgraph.c | 2 +- kernel/trace/trace.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c index d7d4fb403f6f0..47aa5c8d8090e 100644 --- a/kernel/trace/fgraph.c +++ b/kernel/trace/fgraph.c @@ -534,7 +534,7 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, if (!current->ret_stack) return -EBUSY; - BUILD_BUG_ON(SHADOW_STACK_SIZE % sizeof(long)); + BUG_ON(SHADOW_STACK_SIZE % sizeof(long)); /* Set val to "reserved" with the delta to the new fgraph frame */ val = (FGRAPH_TYPE_RESERVED << FGRAPH_TYPE_SHIFT) | FGRAPH_FRAME_OFFSET; diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index c3b2c7dfadef1..0f2ec3d30579f 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2887,7 +2887,7 @@ trace_function(struct trace_array *tr, unsigned long ip, unsigned long /* Allow 4 levels of nesting: normal, softirq, irq, NMI */ #define FTRACE_KSTACK_NESTING 4 -#define FTRACE_KSTACK_ENTRIES (PAGE_SIZE / FTRACE_KSTACK_NESTING) +#define FTRACE_KSTACK_ENTRIES (SZ_4K / FTRACE_KSTACK_NESTING) struct ftrace_stack { unsigned long calls[FTRACE_KSTACK_ENTRIES];